How does your game fit the theme?
It's underwater. I originally intended on the character moving from level to level by going through the bottom part of the level, hence "going deeper" but instead I made that the win condition since I ran out of time to make more levels.

Did you write all the code and made all the assets from scratch?
I wrote all the code. Some of it was from tutorials other pieces were written by me. Any sprite/audio fx were made by others.